AEI zeolite is a crystalline aluminosilicate which is expected to be used in various catalyst applications such as catalysts for olefin production (Patent Literature 1). AEI zeolite has a structure similar to that of CHA zeolite. Due to these facts, AEI zeolite is also expected to be used as a selective catalytic reduction catalyst (so-called SCR catalyst) (Non-Patent Literature 1).
As of the present, the following have been reported as specific AEI zeolite.
Patent Literature 1 is the first report relating to AEI zeolite. Patent Literature 1 discloses SSZ-39 obtained with an N,N-diethyl-2,6-dimethylpiperidinium cation as a structure-directing agent.
Patent Literature 2 discloses SSZ-39 obtained using aluminum nitrate and TEOS (tetraethyl orthosilicate) as raw materials and an N,N-diethyl-2,6-dimethylpiperidinium cation as a structure-directing agent, in the presence of hydrogen fluoride.
Non-Patent Literature 1 discloses SSZ-39 obtained using sodium silicate and USY zeolite as raw materials and a N,N-diethyl-3,5-dimethylpiperidinium cation as a structure-directing agent.
Non-Patent Literature 2 discloses that SSZ-39 is obtained only when certain structure-directing agents of cyclic quaternary ammonium cations are used and the molar ratio of the raw materials SiO2/Al2O3 is 30.
However, in the AEI zeolites reported up to now, the acid site has not been modified and acid strength is too high. In catalyst applications such as hydrocarbon conversion catalysts, side reactions tend to occur with catalysts of which the acid strength is too high.
Additionally, in the AEI zeolites, a cyclic quaternary ammonium cation must be used as a structure-directing agent. However, cyclic quaternary ammonium cations used in the production of SSZ-39 are not generally distributed. For this reason, industrial application of production methods using such structure-directing agents has been difficult. Additionally, in production methods of AEI zeolite up to now, yield and productivity have been low.